<message-box/> is a Web component implemented on Lit-Element library. It is similar to native HTML Element and could runs in mainstream browsers without any difference.

In short, it is a container contains a message string box and some buttons, which common application scenario is to convey to the website user some information. For example:

<message-box class="colorful" >
  <span slot="message">
    This is an example that contains only one option.
  </span>
  <button slot="button">Okay</button>
</message-box>

It looks like this:

Another common scenario is progress bar. Message-box has a progress bar via gradient background color:

More examples can be found here.

npm CDNs like unpkg.com can directly serve files that have been published to npm. This works great for standard JavaScript modules that the browser can load natively.

So recommended ways of importing:

<!-- Importing -->
<script type="module">
  import 'https://unpkg.com/@lit-component/message-box?module';
  ...
</script>
<!-- Using -->
<message-box .../>

Or:

<!-- Importing -->
<script type="module" src="https://unpkg.com/@lit-component/message-box?module"></script>
<!-- Using -->
<message-box .../>

1. Installation via NPM

npm i @lit-component/message-box

2. Importing

In webpack entry script, usually, index.js:

import '@lit-component/message-box'

In HTML:

<message-box .../>

Note that to avoid XSS attacks, DO NOT pass in non-hard-coded content.

generator is using for generates a <message-box/> quickly:

import { generator } from '@lit-component/message-box'

const mountPoint = document.body

const $messageBox = generator(
  `
    <span slot="message">
      This is an example that contains only one option.
    </span>
    <button slot="button">Okay</button>
  `,
  { out: 'right' },
  {
    position: 'fixed',
    top: '2vh',
    'z-index': 'max', // MessageBox will automatically calculate the maximum `z-index` based on mountPoint
  },
  mountPoint
)

mountPoint.appendChild($messageBox)

Its interface is:

/**
 * For quickly generate a message-box
 *
 * @param children        - children of `<message-box/>`
 * @param propertiesDict  - properties dictionary for initialize, optional
 * @param stylesDict      - stylesheet dictionary for initialize, optional
 * @param mountPoint      - reference to mount point element for computing style, optional
 * @param doc             - reference to document, optional
 * @returns {MessageBox} instance
 */
function generator(
  children: HTMLElement | HTMLElement[] | string,
  propertiesDict: PropertiesDict = {},
  stylesDict: StylesDict = {},
  mountPoint: HTMLElement | null = null,
  doc: Document = document,
): MessageBox

You can set attributes for <message-box/> elements directly or properties for Web Component MessageBox instances, and they have the same effect:

<message-box min-width="20vw"/>

<!-- Is equal to -->

<message-box/>
<script>
  const $messageBox = document.querySelector('message-box')
  $messageBox.minWidth = '20vw'
</script>